1. Technical Field
A method of forming a gate oxide film for high voltage region of a flash memory device is disclosed.
2. Discussion of the Related Art
A flash memory device includes a cell region having a cell transistor for storing and erasing data by way of tunneling, and a peripheral circuit unit for driving the cell transistor. The peripheral circuit unit is divided into a low voltage region having a low voltage transistor for applying a low voltage, a high voltage region having a high voltage transistor having resistance against a high voltage of about 20V, which is necessary for tunneling, and the like.
A gate oxide film for high voltage and a gate oxide film for low voltage of a predetermined thickness are formed in each of the regions. When forming the gate oxide film for high voltage, which is thicker than the gate oxide film for low voltage, there is a problem in that a “bird's beak phenomenon” is easily generated.